title: Spica prunellae promotes cancer cell apoptosis, inhibits cell proliferation and tumor angiogenesis in a mouse model of colorectal cancer via suppression of stat3 pathway.
abstract: BACKGROUND
  Constitutive activation of STAT3 is one of the major oncogenic pathways involved in the development of various types of malignancies including colorectal cancer (CRC); and thus becomes a promising therapeutic target. Spica Prunellae has long been used as an important component in many traditional Chinese medicine formulas to clinically treat CRC. Previously, we found that Spica Prunellae inhibits CRC cell growth through mitochondrion-mediated apoptosis. Furthermore, we demonstrated its anti-angiogenic activities in vivo and in vitro. To further elucidate the precise mechanism of the potential tumoricidal activity of Spica Prunellae, using a CRC mouse xenograft model, in this study we evaluated its therapeutic efficacy against CRC and investigated the underlying molecular mechanisms.
  
  
  METHODS
  CRC mouse xenograft model was generated by subcutaneous injection of human colon carcinoma HT-29 cells into nude mice. Animals were given intra-gastric administration with 6 g/kg of the ethanol extract of Spica Prunellae (EESP) daily, 5 days a week for 16 days. Body weight and tumor growth were measured every two days. Tumor growth in vivo was determined by measuring the tumor volume and weight. HT-29 cell viability was examined by MTT assay. Cell apoptosis and proliferation in tumors from CRC xenograft mice was evaluated via immunohistochemical staining (IHS) for TUNEL and PCNA, and the intratumoral microvessel density (MVD) was examined by using IHS for the endothelial cell-specific marker CD31. The activation of STAT3 was evaluated by determining its phosphorylation level using IHS. The mRNA and protein expression of Bcl-2, Bax, Cyclin D1, VEGF-A and VEGFR2 was measured by RT-PCR and IHS, respectively.
  
  
  RESULTS
  EESP treatment reduced tumor volume and tumor weight but had no effect on body weight change in CRC mice; decreased HT-29 cell viability in a dose-dependent manner, suggesting that EESP displays therapeutic efficacy against colon cancer growth in vivo and in vitro, without apparent toxicity. In addition, EESP significantly inhibited the phosphorylation of STAT3 in tumor tissues, indicating its suppressive action on the activation of STAT3 signaling. Consequently, the inhibitory effect of EESP on STAT3 activation resulted in an increase in the pro-apoptotic Bax/Bcl-2 ratio, decrease in the expression of the pro-proliferative Cyclin D1 and CDK4, as well as down-regulation of pro-angiogenic VEGF-A and VEGFR-2 expression. Finally, these molecular effects led to the induction of apoptosis, the inhibition of cell proliferation and tumor angiogenesis.
  
  
  CONCLUSIONS
  Spica Prunellae possesses a broad range of anti-cancer activities due to its ability to affect STAT3 pathway, suggesting that Spica Prunellae could be a novel potent therapeutic agent for the treatment of CRC.
authors.forename: Wei
authors.initials: W
authors.lastname: Lin
authors.forename: Liangpu
authors.initials: L
authors.lastname: Zheng
authors.forename: Qunchuan
authors.initials: Q
authors.lastname: Zhuang
authors.forename: Jinyan
authors.initials: J
authors.lastname: Zhao
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Cao
authors.forename: Jianwei
authors.initials: J
authors.lastname: Zeng
authors.forename: Shan
authors.initials: S
authors.lastname: Lin
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.forename: Jun
authors.initials: J
authors.lastname: Peng
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D004195:Disease Models, Animal; D015536:Down-Regulation; D019073:HT29 Cells; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008928:Mitochondria / Q000187:drug effects; D009389:Neovascularization, Pathologic / Q000188:drug therapy*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use*; D031347:Prunella; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D010936:Plant Extracts; D050796:STAT3 Transcription Factor; D042461:Vascular Endothelial Growth Factor A; D051028:bcl-2-Associated X Protein